Multifocal diffractive ophthalmic lens using suppressed diffractive order

Abstract

To provide a multifocal ophthalmic lens which includes an ophthalmic lens and a diffractive element.SOLUTION: A multifocal ophthalmic lens includes an ophthalmic lens and a diffractive element. The ophthalmic lens has a base curvature corresponding to a base power. The diffractive element produces constructive interference in at least four consecutive diffractive orders corresponding to a range of vision between near and distance vision. The constructive interference produces a near focus, a distance focus corresponding to the base power of the ophthalmic lens, and an intermediate focus between the near focus and the distance focus. A diffraction efficiency of at least one of the diffractive orders is suppressed to less than 10 percent.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This application claims priority to U.S. Provisional Application No. 61 / 993,892, filed May 15, 2014.

[0002] The present invention relates generally to multifocal ophthalmic lenses, and more specifically to multifocal diffractive ophthalmic lenses with suppressed diffraction orders. [Background technology]

[0003] The human eye functions to provide vision by refracting light through a clear outer portion called the cornea and refracting it through the lens onto the retina. The quality of the focused image depends on many factors, including the size and shape of the eye and the transparency of the cornea and lens. When the lens becomes abnormal due to age or disease, vision is reduced due to loss of image quality on the retina. This loss of optical quality in the eye's lens is medically known as cataracts. The accepted treatment for this condition is surgical removal of the lens and replacement of the lens function with an artificial intraocular lens (IOL). As the eye ages, it may also lose its ability to change focus to closer locations, known as accommodation. This age-related loss of accommodation is known as presbyopia.

[0004] In the United States, the majority of cataractous lenses are removed by a surgical technique called phacoemulsification. During this procedure, a portion of the anterior capsule is removed and a thin phacoemulsification cutting tip is inserted into the affected lens and ultrasonically vibrated. The vibrating cutting tip liquefies or emulsifies the nucleus and surface layers of the lens, allowing the lens to be aspirated from the eye. Once removed, the nucleus and surface layers of the lens are replaced in the remaining capsule by an artificial intraocular lens (IOL). The implanted IOL may be a multifocal lens to at least partially restore the patient's ability to see clearly at close range.

[0005] One common type of multifocal lens is a diffractive lens, such as a bifocal lens that provides distance vision and near (or intermediate) vision. Trifocal diffractive lenses are also available, providing additional foci and, at least potentially, a wider range of focusing vision. However, there are disadvantages associated with the division of light energy between multiple foci, particularly within trifocal lenses. Thus, a need remains for improved multifocal diffractive lenses. Summary of the Invention

[0006] In various embodiments of the present invention, a multifocal ophthalmic lens includes an ophthalmic lens and a diffractive element. The ophthalmic lens has a base curvature corresponding to a base power. The diffractive element produces constructive interference for at least four consecutive diffraction orders corresponding to a vision range between near and far vision. The constructive interference produces a near focus, a far focus corresponding to the base power of the ophthalmic lens, and an intermediate focus between the near and far foci. The diffraction efficiency of at least one of the diffraction orders is suppressed to less than 10 percent. This application encompasses the following inventions: (1) an ophthalmic lens having a base curvature corresponding to a base power; and 1. An intraocular lens comprising a diffractive profile disposed on at least one of an anterior and posterior surface, the diffractive profile including a plurality of annular zones shaped to provide constructive interference in at least four successive diffraction orders corresponding to a range of visual acuity, the four consecutive diffraction orders include a lowest diffraction order, a highest diffraction order, and two intermediate diffraction orders; and at least one of the two intermediate diffraction orders is a suppressed diffraction order; the constructive interference produces a near focus, each corresponding to a different one of the four consecutive diffraction orders, a far focus corresponding to a base power of the intraocular lens, and an intermediate focus; and the lowest diffraction order of the successive diffraction orders corresponds to a far focus; and the diffraction efficiency of said lowest diffraction order is higher than any other of the successive diffraction orders; Intraocular lens. (2) The intraocular lens described in (1), wherein the diffraction efficiency of at least one of the diffraction orders is suppressed to less than 10%. (3) The lens of (2), wherein at least a portion of the energy associated with the suppressed orders is redistributed to one or more of the near focus, intermediate focus, and far focus. (4) the four consecutive diffraction orders include a lowest diffraction order, a highest diffraction order, and two intermediate diffraction orders; and 2. The lens of claim 1, wherein the at least one suppressed diffraction order is one of the two intermediate diffraction orders. (5) The intraocular lens of (1), wherein the four consecutive diffraction orders include at least two of the following diffraction orders: -4, -3, -2, -1, 0, +1, +2, +3. (6) The intraocular lens described in (1), wherein the far focus corresponds to the 0th diffraction order. (7) The intraocular lens according to (1), wherein the far focus corresponds to a diffraction order other than the zeroth order. (8) The intraocular lens described in (1), wherein the area diffraction profile includes a repeating set of diffraction steps. (9) The intraocular lens described in (1), wherein the near focus corresponds to vision at 40 cm and the intermediate focus corresponds to vision at 60 cm. (10) an ophthalmic lens having a base curvature corresponding to a base power; and 1. An intraocular lens comprising a diffractive profile disposed on at least one of an anterior and posterior surface, the diffractive profile including a plurality of annular zones shaped to provide constructive interference in at least four successive diffraction orders corresponding to a range of visual acuity, the constructive interference produces a near focus, a far focus, a near-intermediate focus, and a far-intermediate focus for a base power of the intraocular lens, each of which corresponds to a different one of the four consecutive diffraction orders; and the near focus, the near-intermediate focus, and the far-intermediate focus each corresponding to a different add power relative to the base power; the first add power corresponding to the far-intermediate focus is less than one-half the third add power corresponding to the near focus, and the second add power corresponding to the near-intermediate focus is greater than half the third add power corresponding to the near focus; Intraocular lens. (11) the four consecutive diffraction orders include a lowest diffraction order, a highest diffraction order, and two intermediate diffraction orders; and The intraocular lens of (10), wherein one of the diffraction orders is suppressed. (12) the four consecutive diffraction orders include a lowest diffraction order, a highest diffraction order, and two intermediate diffraction orders; and The intraocular lens of (11), wherein the at least one suppressed diffraction order is any one of the two intermediate diffraction orders. (13) The intraocular lens of (12), wherein at least a portion of the energy associated with the at least one suppressed order is redistributed to one or more of the near focus, intermediate focus, and far focus. (14) the four consecutive diffraction orders include a lowest diffraction order, a highest diffraction order, and two intermediate diffraction orders; and The intraocular lens of (10), wherein the diffraction efficiency of the lowest diffraction order is higher than any of the other successive diffraction orders. (15) The intraocular lens of (10), wherein the four consecutive diffraction orders include at least two of the following diffraction orders: -4, -3, -2, -1, 0, +1, +2, +3. (16) The intraocular lens according to (10), wherein the far focus corresponds to the zeroth diffraction order. (17) The intraocular lens according to (10), wherein the far focus corresponds to a diffraction order other than the zeroth order. (18) The intraocular lens described in (10), wherein the multiple annular band diffractive structures include multiple repeating diffractive steps. (19) An ophthalmic lens having a base curvature, an anterior surface, and a posterior surface; and 1. A multifocal ophthalmic lens comprising a diffractive element disposed on at least one of an anterior surface and a posterior surface, the diffractive element including a plurality of annular diffractive steps each having a corresponding step height relative to the base curvature, the plurality of annular diffractive steps including at least two repeating sets of three diffractive steps, the step heights for the three diffractive steps in each repeating set being determined according to the following formula:

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[0007] Other features and advantages of various embodiments of the invention will become apparent to those skilled in the art from the following description. [Brief description of the drawings]

[0008] [Figure 1] 1 illustrates an intraocular lens according to certain embodiments of the present invention. [Diagram 2] 1 illustrates a diffractive step arrangement according to certain embodiments of the present invention. [Diagram 3] 1 is a table illustrating certain diffractive step configurations according to certain embodiments of the present invention. [Figure 4] 1 is a table illustrating certain diffractive step configurations according to certain embodiments of the present invention. [Diagram 5] 1 is a table illustrating certain diffractive step configurations according to certain embodiments of the present invention. [Figure 6] 1 is a table illustrating certain diffractive step configurations according to certain embodiments of the present invention. [Figure 7] 1 is a table illustrating certain diffractive step configurations according to certain embodiments of the present invention. [Figure 8] 1 is a table illustrating certain diffractive step configurations according to certain embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Various embodiments of the present invention provide a multifocal diffractive ophthalmic lens with at least one suppressed diffraction order. By suppressing one diffraction order, the performance of the lens can be adapted to that of a conventional diffractive lens. Known trifocal diffractive lenses split light between multiple diffractive foci, such as (-1, 0, +1) or (0, +1, +2) order foci.

[0010] In contrast, various embodiments of the present invention provide at least three focal points corresponding to the diffraction orders and suppress at least one intermediate diffraction order. This provides intermediate focal points closer to the distance or near vision and provides a wider range of vision around each focal point. Furthermore, suppression of other intermediate orders may distribute more energy to other focal points to provide more useful vision. In the following description, references to ophthalmic lens focal points refer to the corresponding diffractive focal points in the vision range that extends from normal near vision around 30 cm to distance vision (essentially modeled as collinear rays from a finite distance). This excludes the higher orders of the diffractive lens' unwanted waves that exist outside the vision range and provide only unwanted optical effects. Thus, for example, even a nominally bifocal diffractive lens contains higher order diffractive focal points from constructive interference, but for the purposes of this specification, they should not be considered as ophthalmic lens focal points.

[0011] In another embodiment, the multifocal diffractive lens produces foci corresponding to at least four consecutive diffraction orders, including at least one focus less than half the nearest add power and at least one other focus greater than half the nearest add power. This may be more advantageous than a conventional trifocal lens with an add power half the nearest add power. This intermediate vision corresponds to twice the near vision distance, so if the near add power corresponds to a working distance of 40 cm, the intermediate viewing distance, which is a conventional reading distance, would be 80 cm. If a common intermediate working distance is at 60 cm, this would not provide a clear focus at the most common working distance that would fall between the near and intermediate foci. In contrast, a lens with a focus equivalent to 2 / 3 of the near add power would provide a focus at 60 cm, which corresponds to an intermediate working distance.

[0012] FIG. 1 shows a particular embodiment of a multifocal diffractive ophthalmic lens (IOL) 100 including a diffractive element 102. The diffractive element 102 includes diffractive steps 104 (also known as bands) with feature radial separations for constructive interference at feature foci. In principle, any diffractive element, often called a hologram, that produces constructive interference via phase shifts in interference bands can be adapted for use in such a multifocal diffractive ophthalmic lens. Also, although the diffractive element is shown as an annular band, the bands can also be considered partial, such as semicircular or sectored. The following description refers to a diffractive element 102 including annular diffractive steps 103, but it should be understood by those skilled in the art that appropriate substitutions may be made in any of the embodiments disclosed herein.

[0013] The IOL 100 also includes an optic 104 on which the diffractive element 102 is positioned. The optic 104 determines the base optical power of the lens, which generally corresponds to the patient's distance vision. This need not always be the case, for example, the poorer eye may have an IOL with a base optical power slightly less than the corresponding distance power to improve the overall binocular vision of both eyes of the patient. Nevertheless, the add power of the IOL can be defined in terms of the base optical power. The haptics 106 hold the IOL 100 in place and provide a stable anchoring within the capsular bag. Although haptic arms are shown in the example, any suitable haptic anchoring structure for the capsular bag or ciliary sulcus compatible with posterior chamber implantation can also be used with posterior chamber IOLs.

[0014] Although the following examples deal with a posterior chamber IOL 100, other ophthalmic lenses, including multifocal diffractive spectacles and multifocal diffractive contact lenses, can also benefit from the same approach. This known and fixed lens position relative to the optical axis makes such applications convenient for intraocular lenses, including intracorneal, anterior chamber, and posterior chamber lenses. However, this does not preclude the usefulness of multifocality in other applications.

[0015] FIG. 2 illustrates in more detail a diffractive step structure useful in an ophthalmic lens such as the IOL 100 of FIG. 1. In particular, FIG. 2 illustrates a three-step repeating diffractive structure that produces a phase relationship for constructive interference at four distinct foci within the visual field. 2 The step relationship for successive radial step boundaries along a scaled radial axis (x-axis), measured in -space, is:

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[0016] In the formula, A i is the corresponding step height (constant phase lag φ i excluding y i is the sag (height above and below the x-axis) in the corresponding segment, and φ i is the relative phase lag from the x-axis, and x i is the position of the step along the x-axis. As will be appreciated by those skilled in the art of diffractive optics, the radial positions shown in the formulas correspond to the r 2 -space (i.e., scaled parabolically). In a particular embodiment, the parameters are selected so that one of the foci is suppressed, i.e. the light energy is reduced for a section in the foci such that the focused image is no longer visible. This is also suggested by the fact that bifocal lenses with undesired diffraction orders corresponding to less than 10% of the incident light energy do not result in a separately visible image. The fraction of the incident light energy that is focused in a particular order will be referred to as the "diffraction efficiency".

[0017] The listed phase relationships are given with respect to a base curve determined by the base power of the IOL, and correspond to the zero order diffractive focus of the lens. Adjustments to the relative phase relationships between the components can be varied in a manner known in the art to slightly modify the energy distribution between the foci, but not to the band x i The radial spacing of the r is usually determined by the diffraction add power. 2- is determined based on the normal Fresnel band spacing in space. In the examples listed below, this spacing should be assumed according to known Fresnel patterns to produce four foci. This is similar to the trifocal approach described, for example, in U.S. Patents 5,344,447 and 5,760,817 and PCT Publication WO 2010 / 0093975, all of which are incorporated by reference. Diffractive steps can also be apodized (gradually reduced in step height relative to the nominal phase relationship) to reduce glare by progressively reducing energy to the near focus in the manner described in U.S. Patent 5,699,142.

[0018] 3-8 provide an exemplary multifocal embodiment for a (0, +1, +2, +3) diffractive lens, in which the +1 order is suppressed. This advantageously provides an intermediate focus at ⅔ of the near add power, corresponding to focused images at distances of 60 cm and 40 cm, respectively. Notably, the diffraction efficiency for the distance vision (zero order) focus can be nearly 40%, comparable to that of a conventional bifocal lens, and the diffraction efficiency for the suppressed primary focus can be less than 5%, while still providing visible intermediate and near foci at the normal working distances of 60 cm and 40 cm, respectively. Compared to conventional multifocals, this nicely approximates the full range of working vision that a patient would use if they were not presbyopic.

[0019] Although specific embodiments have been described herein, those skilled in the art will appreciate that numerous variations are possible. In particular, the embodiment described herein is a multifocal posterior chamber IOL using (0, +1, +2, +3) diffractive orders with the +1 order suppressed. The four order embodiment can use different successive diffractive orders, for example starting with orders from -4 to -1. Although it is desirable to include the zeroth order in the distance vision, such a condition is not a necessary constraint. Finally, the technique can in principle be applied to more than four diffractive orders, for example a five order diffractive lens can have an add power including two intermediate powers, a near power, and a suppressed intermediate power.

Claims

1. an ophthalmic lens having a base curvature; a diffractive element producing constructive interference for four successive diffraction orders, the constructive interference produces a near focus, a far focus, and an intermediate focus between the near focus and the far focus; a diffraction efficiency of a first of the four consecutive diffraction orders is at least 37%; a diffraction efficiency of a second of the four consecutive diffraction orders is between 3% and 10%; a diffraction efficiency of a third of the four consecutive diffraction orders is between 10% and 20%, and A multifocal ophthalmic lens, wherein a diffraction efficiency of a fourth of said four successive diffraction orders is between 15% and 30%.

2. The multifocal ophthalmic lens of claim 1 , wherein the four consecutive diffraction orders are (0, +1, +2, and +3).

3. The multifocal ophthalmic lens of claim 1 , wherein said four consecutive diffraction orders are (−1, 0, +1, and +2).

4. The multifocal ophthalmic lens of claim 1 , wherein the four consecutive diffraction orders are (+1, +2, +3, and +4).

5. the first diffraction order corresponds to the far focus; the third diffraction order corresponds to the intermediate focus; and the fourth diffraction order corresponds to the near focus; The multifocal ophthalmic lens according to claim 1.

6. the four consecutive diffraction orders are (0, +1, +2, and +3); the first diffraction order is a zero order and corresponds to the far focus; the second diffraction order is suppressed at +1 order; the third diffraction order is the +2 order and corresponds to the intermediate focus; and the fourth diffraction order is a +3 order and corresponds to the near focus; The multifocal ophthalmic lens according to claim 1.

7. The multifocal ophthalmic lens of claim 6 , wherein at least a portion of the energy associated with the +1 order is redistributed to the far focus.

8. The multifocal ophthalmic lens of claim 1 , wherein the diffractive element comprises a plurality of annular bands shaped to provide constructive interference in the four successive diffraction orders.

9. The multifocal ophthalmic lens of claim 8 , wherein the plurality of annular bands comprises a plurality of repeating diffractive steps.

10. 2. The multifocal ophthalmic lens of claim 1, wherein the four consecutive diffraction orders include at least two of the following diffraction orders: -4, -3, -2, -1, 0, +1, +2, and +3.

11. The multifocal ophthalmic lens of claim 1 , wherein the ophthalmic lens is an intraocular lens.

12. 2. The multifocal ophthalmic lens of claim 1, wherein the near focus corresponds to visual acuity at 40 cm and the intermediate focus corresponds to visual acuity at 60 cm.

13. 8. A multifocal ophthalmic lens according to claim 7, wherein said near focus corresponds to visual acuity at 40 cm and said intermediate focus corresponds to visual acuity at 60 cm.

14. an ophthalmic lens having a base curvature; a diffractive element producing constructive interference for five successive diffraction orders, the five consecutive diffraction orders include a lowest diffraction order, a highest diffraction order, a first intermediate diffraction order, a second intermediate diffraction order, and a third intermediate diffraction order; and the third intermediate diffraction order is suppressed; Multifocal eye lenses.

15. The multifocal ophthalmic lens of claim 14, wherein the five consecutive diffraction orders include at least two of the following diffraction orders: -4, -3, -2, -1, 0, +1, +2, and +3.

16. 15. The multifocal ophthalmic lens of claim 14, wherein the constructive interference produces a near focus, a far focus, a first intermediate focus, and a second intermediate focus, each corresponding to a different one of the five consecutive diffraction orders.

17. The multifocal ophthalmic lens of claim 16, wherein the far focus corresponds to the zeroth diffraction order.

18. 17. A multifocal ophthalmic lens according to claim 16, wherein the far focus corresponds to a diffraction order other than the zeroth diffraction order.

19. 15. A multifocal ophthalmic lens according to claim 14, wherein the diffraction efficiency of the lowest diffraction order is higher than the diffraction efficiency of any other successive diffraction order.

20. The multifocal ophthalmic lens of claim 14, wherein the ophthalmic lens is an intraocular lens.

21. 15. The multifocal ophthalmic lens of claim 14, wherein the five consecutive diffraction orders are 0, +1, +2, +3, and +4.

22. 15. The multifocal ophthalmic lens of claim 14, wherein the five consecutive diffraction orders are +1, +2, +3, +4, and +5.

23. The multifocal ophthalmic lens of claim 14, wherein the diffraction efficiency of the highest diffraction order is higher than the diffraction efficiency of the first intermediate diffraction order, the second intermediate diffraction order, and the third intermediate diffraction order.

24. an ophthalmic lens having a base curvature, an anterior surface, and a posterior surface; 1. A multifocal ophthalmic lens comprising a diffractive element disposed on at least one of an anterior surface and a posterior surface, the diffractive element including a plurality of annular diffractive steps each having a corresponding step height relative to the base curvature, the plurality of annular diffractive steps including at least two repeating sets of three diffractive steps, the step heights for the three diffractive steps in each repeating set being determined according to the following formula: [0010] (In the formula, Ai is the step height for the base curvature, yi is the sag (height above and below the x-axis) in segment i, φi is the relative phase lag from the x-axis, and and x i is the position of said step along the x-axis.

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